New Zealand Journal of Botany abstracts
Witches’ brooms and frosty pods: two major pathogens of cacao
Gareth W. Griffith
Jean Nicholson
Anja Nenninger
Richard N. Birch
Institute of Biological Sciences
University of Wales Aberystwyth
Penglais
Aberystwyth
Ceredigion SY23 3DD, Wales
Email: gwg@aber.ac.uk
John N. Hedger
School of Life Sciences
University of Westminster
115 New Cavendish Street
London W1M 8JS, England
Abstract The agaric Crinipellis perniciosa
(Tricholomataceae) is a hemibiotrophic pathogen which causes witches’ broom
disease of cacao and has recently decimated the Brazilian cacao industry.
In addition to the pathogenic cacao (C-) biotype, other biotypes are found
in association with unrelated plant taxa, notably bignoniaceous lianas (L-biotype),
solanaceous hosts (S-biotype), and the shrub Heteropterys acutifolia
(H-biotype). The C- and S-biotypes are non-outcrossing and form broom symptoms
on hosts, whereas the L-biotype is outcrossing and asymptomatic. Phylogenetic
analysis of several regions of the rRNA locus revealed near identity between
C- and S-biotype isolates from diverse locations, with the L- and H-biotypes
forming separate groupings. Preliminary analysis of sequence data from Moniliophthora
roreri, causal agent of frosty pod disease, indicates that this morphologically
distinct pathogen may be closely related to C. perniciosa. Similarities
in host infection between C. perniciosa and M. roreri have
previously been noted but it is difficult to reconcile the gross morphological
differences. Pairings between C. perniciosa and M. roreri gave
rise to a clamped dikaryotic mycelium suggestive of a hybridisation event.
Keywords rRNA sequences; phylogenetics; endophytes;
disease control; tropical ecology
B02084 Received 18 December 2002; accepted 16 June 2003; Online publication
date 11 September 2003
New Zealand Journal of Botany, 2003, Vol. 41: 423-435
0028-825X/03/4103-0423 $7.00 © The Royal Society of New Zealand
2003
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